Wind turbine yawing system, wind turbine and yawing process

Abstract

A yawing system for a wind turbine, the wind turbine comprising a tower fixed to the ground and a frame (1) housing an electric power generator, the tower and the frame (1) being joined by the yawing system which allows the orientation of the frame (1) with respect to the tower according to the direction of the wind. The yawing system comprises:

• • a gear ring (2) fixed to the tower, the gear ring having a sliding track (3) on which the frame (1) rests and slides in its yawing movement,
  • at least one geared motor fixed to the frame (1), meshed with the gear ring (2) through a gear wheel,
  • at least one active braking module (5), and
  • at least one passive braking module (6).

The invention further comprises a sliding track (3) and a friction track on the gear ring, this friction track (10) being different from the sliding track (3), and the active braking modules (5) and passive braking modules (6) comprising a friction plate (11) acting on the friction track (10) of the ring. The frame (1) rests on the gear ring (2) by means of horizontal plates (8) and radial plates (9) made of a sliding material, and are kept in their position by separating parts (7). Furthermore, the gear ring (2) is divided into gear-toothed circular segments to favor its repair. Other aspects are a wind turbine with the previous yawing system and a yawing process of a turbine by means of the previous yawing system.

Description

FIELD OF THE INVENTION [0001] The invention is encompassed within the field of wind turbine orientation systems, particularly in reference to the means for moving the rotor of the wind turbine to orient it to the wind and to retain it when it is in its objective position, preventing the same wind from moving it. BACKGROUND OF THE INVENTION [0002] Wind turbines consist of a fixed tower which raises an electric generator connected to a rotor by mechanical means above the ground. The rotor is formed by a hub or base joining one or several blades which are responsible for transforming the kinetic energy of the wind into rotational movement of the rotor. The turbine is generally placed on a frame, which is able to move with respect to the tower supporting it such that it allows the rotor to be oriented in the direction of the wind. One manner of orientation can be letting the frame (forming part of what is usually called the nacelle of the wind turbine) freely rotate (leeward orientation...

AI Technical Summary

Benefits of technology

[0035] When the active braking means are in the first position according to the braking instructions, they push with a first force which can be comprised between zero and a residual braking force. In other words, when the active braking means are in the first position, they can either exert no effect on the yawing system, or they can continue to produce a residual braking which is added to the braking effect of the passive braking modules. When an active braking module is in the second position, it pushes the friction plate of the module against the friction track of the ring with a second force, greater than the first force, producing a greater braking effect.

Problems solved by technology

The problem posed by this process is that once the frame is located in one orientation by means of the motor, it does not remain immobile, but rather gusts of wind can exert a momentum which moves the frame.

Therefore the motor must be constantly running, and the gear teeth of the ring and of the wheel undergo loads in both directions, causing allowances and the deterioration of the gear teeth, which requires costly repairs.

One of them is that the braking systems do not have enough retention capacity against strong gusts of winds.

Increasing the known active braking systems requires a larger friction surface or a greater force for acting on the elements joined to the tower (friction disc or the like), but the weight and space in the upper part of the tower forces making much sturdier towers, increasing the cost of the wind turbine.

Braking by means of drive motors of an acceptable size in the towers themselves is neither enough to prevent movements due to strong gusts of wind.

Another problem is that the elements of the yawing system of the wind turbine, especially the gear ring, the nacelle support ball bearings and the braking systems undergo significant loads, which leads to the frequent need for repairs or replacements.

On the other hand, the gear teeth of the gear ring may undergo wear and tear and / or breakage, and in the known systems, a breakdown in the bearings supporting the nacelle allowing the rotation on the tower, or in the ring where the motor meshes, requires the disassembly of the nacelle, taking it to ground level so as to carry out the repair.

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